Backlink Checker MCP: Referring Domains and Anchors

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description doesn't need to restate that. It adds genuinely useful context the annotations lack: that each call consumes API credits, plus the shape of the result set (one backlink per domain). It could go further on rate limits or failure behavior for invalid targets, which keeps it from a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence naming the tool, then the returned metrics, then the cost caveat—no filler. The metric enumeration is slightly redundant given an output schema exists, which costs it a perfect score, but nothing here is wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter, non-destructive read tool with full schema coverage, rich annotations, and an output schema, the description covers purpose, input scope, and the cost side effect—enough to call it correctly. The one material gap is sibling disambiguation: an agent could reasonably confuse this with get_referring_domains or get_backlink_anchors.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%—both 'target' (domain or full page URL) and 'limit' (1–100, default 25) are fully documented in the schema. The description only echoes the domain-or-URL input scope and adds nothing about the limit parameter or the tradeoff of raising it. Baseline 3 is appropriate when the schema carries the parameter burden.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a concrete verb+resource ('Backlink checker') and enumerates exactly what comes back: total backlinks, referring domains, domain rank, spam score, and top backlinks one per domain. That is far more specific than a restated title. It stops short of a 5 because it never distinguishes itself from the sibling tools, and listing 'referring domains' as one of its outputs overlaps with the get_referring_domains sibling.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'For any domain or URL' implies the input scope and 'costs API credits per call' signals a budget consideration, which nudges usage. However, there is no explicit when-to-use or when-not-to-use guidance, and nothing tells the agent whether to call this or the sibling get_referring_domains / get_backlink_anchors for a given question—which is a real risk given the output overlap.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: the call is free of charge and triggers no upstream supplier call, which tells the agent it is cheap in both cost and latency. It does not discuss caching or freshness of the balance value.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence packs the returned fields and the cost/latency caveat with no filler. The leading 'API credit balance:' label is mildly redundant with the title but functions as a scannable anchor rather than waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema documenting the return shape, zero parameters, and rich annotations, the description's burden is small and it meets it: what the tool reports and that it costs nothing. Only the when-to-use signal is absent, which keeps it short of a 5.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly offers no parameter guidance, which is appropriate rather than a gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names the exact resource (prepaid API credit balance) and enumerates the four facts it exposes: credits remaining, amount spent, suspension status, and per-call pricing rule. An agent can tell this is an account/billing read, distinct in substance from the SEO-data siblings, though no sibling is named explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: 'Free; no supplier call' hints it is safe to call speculatively (e.g., to verify credits before paid SEO queries), but the description never states when to use it or what alternative exists. Nothing misleads, but the agent must infer the check-before-spending workflow.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare read-only, idempotent, open-world, non-destructive behavior, so the bar is lower. The description adds a genuinely useful trait annotations cannot express: that each call consumes API credits, which lets the agent budget calls. It stops short of saying how many credits or whether pagination applies.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two compact sentences: the first front-loads what the tool returns, the second flags the cost. No filler, no restating of the title in a wasteful way, and the cost warning sits at the end where it reads cleanly.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return shape need not be explained, and annotations plus full param coverage carry the safety and input burden. The description covers purpose and the credit cost, leaving only minor gaps such as credit amount and result ordering, which is sufficient for a simple two-parameter read tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so both `target` (domain vs full page URL) and `limit` (1-500, default 100) are already fully documented. The description adds no syntax, format, or constraint detail beyond the schema, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Names the specific resource (anchor texts of backlinks) and its scope (links to a domain or full URL), plus what metrics accompany each anchor. It is distinguishable from get_referring_domains and check_backlinks by the anchor-text framing, though it never names those siblings explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The purpose statement implies when the tool is appropriate (you want the anchor-text distribution for a target), but there is no explicit when-to-use/when-not guidance and no pointer to the sibling tools. Nothing is misleading, but the routing decision is left to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already establish that this is a safe, idempotent, read-only operation, so the description does not need to repeat that. It adds useful behavioral context by disclosing that calls cost API credits and that results are ordered strongest first.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single efficient sentence that front-loads the resource, lists the key return fields, states ordering, and appends the cost notice. Every clause carries relevant information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a two-parameter read-only tool with annotation coverage and an output schema, the definition is largely complete. The main gap is that it does not distinguish this tool from closely related backlink tools, but the core behavior and cost are clear.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so both parameters are already documented in the schema. The description reinforces that target can be a domain or full URL, but adds no syntax or constraint details beyond the schema and does not mention the limit parameter.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the resource: domains linking to a domain or URL, and specifies the returned fields and ordering. It is more specific than a tautology, but it does not differentiate this tool from siblings such as check_backlinks or get_backlink_anchors.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives no explicit when-to-use guidance or alternatives. An agent can infer that this lists referring domains, but nothing says when to choose it over check_backlinks or get_backlink_anchors.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.