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

Annotations already establish a non-destructive write (readOnlyHint=false, destructiveHint=false), so safety is covered. The description adds only the HTTP verb/path, saying nothing about whether the change affects in-flight sessions, requires ownership of the key, or is reversible.

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 short, front-loaded sentences with the core action first. The raw endpoint path is somewhat redundant filler given the name, but nothing else 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 mutation tool with a nested body, no output schema, and near-zero parameter documentation, the description is too thin: no prerequisites, no effect of the change, no link between the id and the key being modified.

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 effectively 0% per signals (only the nested modelId carries a terse note). The description never explains that 'id' is the API key identifier or that modelId must reference an existing LLM model, so it fails to compensate for the undocumented parameters.

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 ('Update model for an API key') plus the underlying endpoint, so the operation is unambiguous. It does not name or contrast any sibling such as get_api_llm or post_api_llm, and the term 'API key' is a loose stand-in for the LLM configured key.

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?

No explicit when-to-use, when-not-to-use, or alternative is given. An agent must infer that this changes the model bound to an existing LLM key rather than creating (post_api_llm) or deleting (delete_api_llm_id) it.

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