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

Annotations only give generic hints (readOnly=false, destructive=false, non-idempotent); the description adds real behavioral facts: the rule is account-wide and lasting, matching is substring-based for KEYWORD/JOB_TITLE with a concrete warning about over-broad terms, and rules cannot be deleted afterwards.

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?

Front-loaded with what the tool does, then the matching caveat, then the routing alternatives. Every clause carries distinct information; nothing is restated from the title or schema verbatim.

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 3-parameter mutation with no output schema, the description covers scope, matching semantics, alternatives, and irreversibility. The only omission is what the call returns (e.g., a created rule id), which is minor given no output schema exists.

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 the baseline is 3, but the description adds operational meaning beyond the schema by explaining that keyword values are matched as substrings against the profile and must be kept specific, plus the concrete failure mode ('director' would exclude a large slice).

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?

Opens with a specific verb ('Exclude') and enumerates the exact matchable resources (profile URL, company URL, keyword, job title, email). It is immediately distinguishable from siblings by naming `lead_update`/`isExcluded` and `blacklist_add_bulk` as different routes.

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?

Explicitly states when not to use it ('not a way to skip one prospect in one campaign, which is `lead_update` with `isExcluded`') and which tool handles batches (`blacklist_add_bulk`). It even closes the loop on rule removal by stating no delete tool exists.

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