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

Annotations only declare the safety/scope profile (not read-only, closed-world, non-idempotent, non-destructive); the description adds real behavior the annotations miss — that omitting content wipes the file body, that only one conventional file name is meaningful in v1, and that multi-file support is future work. It does not cover permissions or what happens to a file that doesn't yet exist (upsert creates it, but that's inferred from the verb rather than stated).

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 sentences, front-loaded with the verb and resource, followed by the naming convention and clearing semantics in order of usefulness. The forward-looking 'future versions will support multiple named files' clause is mild roadmap noise but arguably useful context for the v1 limitation.

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 full schema coverage, annotations, and no output schema, the description covers the essentials: what gets written, where, the naming convention, and how to clear a file. Missing only error/permission behavior and confirmation of create-vs-update, which are secondary here.

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 every parameter (name, format, content, board_id) is documented in the schema itself, including the AGENTS.md convention and the clear-by-empty rule. The description restates rather than extends that information, so baseline 3 is appropriate.

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 ("Upsert a named markdown file on a board") and pins the v1 convention to "AGENTS.md" (the root prompt), which makes the tool unambiguous. It also positions itself as the low-level writer beneath update_board's prompt option, distinguishing it from that sibling, though it never names the read-side siblings (get_board_prompt, list_board_files).

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 concrete usage context: use "AGENTS.md" for the root prompt in v1, and omit or pass empty content to clear the body. The reference to update_board's prompt option implies the higher-level alternative, but there is no explicit 'use X instead when...' directive or exclusion list.

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