SEO Backlink Value

seo-backlink-value

Value a backlink offer the way a buyer should: veto bad sites first, then price the good ones against a market band and the seller's quote. Deterministic, stdlib-only, no network. The agent supplies the metrics; this skill only computes.

When to use

• The user has one or more link offers (guest post, homepage/sitewide, niche edit, directory listing, nofollow/sponsored) and asks whether to buy, what a fair price is, or which to buy first.
• A strategy or off-page recommendation needs a defensible price ceiling for a proposed link placement.

When NOT to use

• Discovering candidate sites or fetching DR, traffic, or keyword data. Those come from the user, a connected console, or a paid tool the user already has; this skill has no data source of its own.
• On-page, technical, or GEO scoring of the user's own site (seo-tech-audit, geo-score).

Acquire the metrics before calling (agent work)

The user should not have to look numbers up. Fill each offer's metrics in this order and record the source of every value in sources:

1. A connected SEO data provider (Ahrefs, Semrush, Moz, DataForSEO, SimilarWeb, SE Ranking) through the connector tools: list the connected tools, call the domain-overview / backlink-profile operation, and map DR or DA, monthly organic traffic, organic share, trend and referring domains into metrics with sources naming the provider. These are the only figures that may be reported as provider-measured.
2. Free public endpoints with web_fetch when no provider is connected. Pass what they return in proxies; the skill converts them into conservative tier estimates and labels the whole result public_proxy:
   • Popularity rank and 30-day history: https://tranco-list.eu/api/ranks/domain/<domain> → {"domain","ranks":[{"date","rank"}]}. Put the latest rank in proxies.tranco_rank (or null when the response lists no ranks) and the full array in proxies.tranco_history.
   • Domain age: RDAP. Look up the TLD's server in https://data.iana.org/rdap/dns.json, then fetch <server>/domain/<domain> (for .com/.net: https://rdap.verisign.com/com/v1/domain/<domain>) and pass the registration event's eventDate as proxies.rdap_registration.
   • Indexation: a web_search for site:<domain>; pass the visible result count as proxies.site_results (0 leaves indexation unknown). Set metrics.indexed: false only from verified index-status evidence, not search absence. Organic share has no free source; leave it out and say so.
3. Ask the user only for what steps 1–2 could not supply, naming the exact field. Never scrape the web UI of Ahrefs, SimilarWeb, Semrush or Moz free checkers: they are login- or CAPTCHA-gated and their terms forbid it.

Preconditions

• Python 3.9+ (stdlib only).
• Per offer: domain, and at least dr (or da) and monthly_traffic — supplied in metrics or derivable from proxies (a Tranco rank is enough for both). Optional: organic_share (0–1 or percent), traffic_trend (fraction over the last months, e.g. -0.2), domain_age_years, outbound_links_on_page, relevance (high|medium|low to the buyer's topic), indexed (bool), link_type, quoted_price_usd, market_prices (observed listing prices of comparable sites, at least five to replace the reference table), sources ({metric: provider}), proxies (see above) and as_of (ISO date used to turn the registration date into an age; defaults to today).
• Supplied metrics always win over proxies. Seller-claimed figures are sources: "seller" and stay Estimated. Without dr and monthly_traffic from any of the three steps the skill returns insufficient_evidence and names what is missing; nothing is guessed.

How to call

Evaluate one offer (payload on stdin or --input <file>):

echo '{"domain":"example-blog.com","link_type":"guest_post","quoted_price_usd":150,"metrics":{"dr":45,"monthly_traffic":30000,"organic_share":0.62,"traffic_trend":0.05,"domain_age_years":6,"relevance":"high"}}' | "$ORKAS_NODE" "$ORKAS_PC_DIR/bin/run-skill.cjs" seo-backlink-value backlink_value -- --op evaluate

With public proxies instead of provider metrics:

echo '{"domain":"example-blog.com","link_type":"guest_post","quoted_price_usd":150,"proxies":{"tranco_rank":120000,"tranco_history":[{"date":"2026-08-10","rank":131000},{"date":"2026-09-08","rank":120000}],"rdap_registration":"2018-04-02T00:00:00Z","site_results":860}}' | "$ORKAS_NODE" "$ORKAS_PC_DIR/bin/run-skill.cjs" seo-backlink-value backlink_value -- --op evaluate

→ { ok, data: { domain, link_type, type_multiplier, metrics, metric_sources:{metric: "supplied"|"<provider>"|"tranco_rank_proxy"|"tranco_history_proxy"|"rdap"|"site_search_proxy"}, gate:{status:"pass"|"avoid"|"insufficient_evidence", reasons[], missing_metrics[]}, quality:{score, tier, components}, market:{bracket, dr_tier, traffic_tier, guest_post_band_usd:{p25, median, p75}, data_tier, basis}, adjustments:[{code, factor, detail}], value_band_usd:{p25, median, p75}, quoted_price_usd, quote:{verdict, detail}, data_tier:"observed_market"|"reference_table"|"public_proxy"|"insufficient_evidence", notes[] } }

Rank several offers (a shared market_prices list applies to every candidate that has none of its own):

echo '{"market_prices":[90,120,150,220,400],"candidates":[{"domain":"a.example","quoted_price_usd":120,"metrics":{...}},{"domain":"b.example","metrics":{...}}]}' | "$ORKAS_NODE" "$ORKAS_PC_DIR/bin/run-skill.cjs" seo-backlink-value backlink_value -- --op rank

→ { ok, data: { candidates:[{...evaluate result, rank}], buy[], negotiate[], avoid[], needs_metrics[] } } — passing sites first by quality per dollar, then sites missing metrics, then vetoed sites.

Method

1. Quality gate (veto). zero_traffic (< 100 visits/month), inflated_traffic (organic share < 15% with material traffic), link_farm (DR ≥ 40 with < 500 visits), deindexed. Any reason → avoid; the band is still returned for reference only.
2. Market band. 8 DR tiers × 6 monthly-traffic tiers = 48 brackets. With ≥ 5 market_prices the band is the 25th/50th/75th percentile of those observations (data_tier: observed_market); otherwise an embedded guest-post reference table supplies the median with p25 = 0.6× and p75 = 1.6× (data_tier: reference_table, always Estimated).
3. Refinements. organic share ≥ 60% +10%; traffic trend ≤ −15% −15%; domain younger than 1 year −10%; more than 50 outbound links on the page −10%; relevance high +10% / low −20%.
4. Link type. guest post ×1.0, homepage/sitewide ×1.3, niche edit ×0.7, directory ×0.5, nofollow ×0.4. Nofollow passes no authority; its value is referral traffic and trust only.
5. Quote verdict. ≤ p25 bargain, ≤ median fair, ≤ p75 negotiate, above overpriced; no quote → the median is the fair offer and p75 the walk-away ceiling.

Reporting

• Present the verdict, the three-point band with its labels (bargain ceiling / fair market / do not buy above), the quality score and tier, and the gate reasons verbatim.
• Label every input by source (metric_sources) and the band by data_tier. A reference-table or public-proxy band is Estimated and must say so; a public_proxy result also states that authority came from popularity rank and that the median is a ceiling until DR is confirmed. Only a band from supplied observed listings may be called market-based, and only provider figures may be called provider-measured. Never call any of it Measured.
• When the gate says avoid, lead with the reason; price is irrelevant.
• Quality tiers: strong ≥ 75, solid ≥ 50, weak ≥ 30, poor below; avoid replaces the tier when the gate fails.