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

Annotations already declare this is a non-read-only, idempotent, non-destructive mutation, so the bar is lower; the description still adds real value by disclosing the cost model (FREE / no credits), calling out that it is a MUTATION, and confirming merge semantics (only fields given here are changed), which is consistent with idempotentHint=true.

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?

Dense but front-loaded: tool category, editable field list, merge semantics, cost, mutation warning, then the exclusion. No sentence is filler and nothing important is buried.

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 an 8-param mutation with no output schema and thin schema descriptions, the reader learns what changes, what stays, what it costs, and where the excluded fields go. Only the return/confirmation behavior is unstated, which is a minor gap given no output schema exists to cover it.

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 only 25% (projectId and prospectId only), so the description must compensate — and it does, naming url/label/targetUrl/contact fields as the editable set and excluding domain/status. It stops short of format or length guidance, but it adds meaning the schema alone does not.

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?

Specific verb (edit/update) plus resource (link-building prospect) with an explicit enumeration of the editable fields. It explicitly distinguishes itself from the closest sibling, update_link_prospect_status, so an agent can tell them apart without opening either schema.

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?

States the routing rule for the ambiguous case (`domain` and `status` are not editable here — use update_link_prospect_status), which is exactly the alternative an agent would otherwise guess wrong on. It does not cover every sibling (e.g. add_link_prospect vs this), but the partial-update intent is unambiguous.

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