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

Annotations flag destructiveHint=true, and the description earns that flag by explaining the merge semantics: omitted fields are preserved, aliases replaces the entire list, and domain null removes the field. That is real behavioral context an agent cannot get from the annotations alone. It stops short of covering failure modes (unknown competitorId, permission requirements) or why the operation is destructive beyond domain removal.

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?

Three short sentences with no filler; the mutable-field list and the merge rule come first, followed by the per-field exceptions and the return value. Every clause carries 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 five-parameter update tool with full schema coverage, no output schema, and annotations covering the safety profile, the description is nearly sufficient: it explains merge semantics, field-specific behaviors, and what is returned. Only error/not-found behavior and required permissions are absent, which are minor for this complexity.

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% and the schema already states that domain null removes it and that aliases replaces the whole list, so most of the description's field notes restate structured data. The one genuine addition is "a field left out keeps its value," which documents partial-update/merge behavior not expressed anywhere in the schema. That lifts it slightly above the baseline but not far, since the remaining notes duplicate the schema.

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 specific verb and resource ("Change a tracked competitor") and enumerates the mutable fields (name, domain, aliases). The update verb cleanly separates it from siblings add_competitor, remove_competitor, and list_competitors.

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 implied by the verb and by the field-level semantics, so an agent can infer this is the tool for modifying an existing competitor. There is no explicit when-to-use/when-not guidance, no mention of what to do if the competitor is missing, and no routing to update_project or update_persona for adjacent resources.

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