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

Annotations already declare destructiveHint=true, so the mutation profile is covered structurally. The description adds only the REST endpoint mapping (PUT /v1/lists/{list_id}/items/{id}), and says nothing about permissions, whether the prior comment is overwritten, or what happens on failure.

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 sentences with the action front-loaded and the API mapping secondary; no filler or redundancy.

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 simple three-parameter, fully-required mutation with no output schema, the description covers the core action adequately. It nevertheless omits behavior an agent would want before calling a destructiveHint tool, such as whether the comment is fully replaced and what a successful response contains.

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 100% and all three parameters are documented (comment, item_id, list_id), so the schema carries parameter meaning. The description adds nothing beyond the schema's own wording, which is the expected baseline when coverage is complete.

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 the comment on a list entry'), which is clearly distinct from sibling mutators like castle_update_list. However, it does not explicitly contrast itself with castle_update_list or castle_archive_list_item, so sibling differentiation rests on the name alone.

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?

There is no statement of when to use this tool versus alternatives such as castle_update_list, nor any prerequisites (e.g., the item must already exist, or that the previous comment is replaced). The only usage cue is the implied meaning of 'Change'.

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