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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuine context beyond that: the scope is the authenticated user's own letters, item bodies are excluded, and a viewUrl is included – but it says nothing about pagination or ordering, which matters for a list endpoint.

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 the action, endpoint and return summary before any routing advice, then closes with the viewUrl note. Every sentence carries either scoping, routing, or chaining information; nothing is padding.

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 single-optional-param, read-only list tool with an output schema, the description covers purpose, routing, what is and isn't returned, and the follow-up workflow. The only gap is pagination/ordering behavior, which the output schema does not make obvious for a potentially long list.

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?

There is a single parameter with 100% schema description coverage, so the schema already explains that userId comes from get_user_profile and is auto-fetched when omitted. The description adds no parameter syntax or defaults of its own; per the coverage rule this lands at the baseline of 3.

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 (list the authenticated user's cover letters) plus the backing endpoint, and enumerates the returned fields. It explicitly separates itself from create_cover_letter, so an agent can distinguish the two 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?

Gives an explicit timing cue ("use early when the user wants to apply a template or export an existing letter"), names the alternative (create_cover_letter) with the condition that selects it ("only when they need a new letter for a job"), and prescribes the downstream chain list_templates → apply_template → export_file.

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