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

Annotations already declare destructiveHint=true and readOnlyHint=false, matching the write operation described. The description adds the context that the note is personal and the post must be saved, but does not elaborate on whether the note is replaced or created if one already exists, which is a behavioral gap for a mutation tool.

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?

The description is a single, clear sentence with no redundant words. It is front-loaded with the core action and resource, making it easy to parse quickly.

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 two-parameter tool with no output schema, the description covers the essential function but omits details like upsert behavior (whether an existing note is overwritten) and the effect of providing a note for an unsaved post. The idempotentHint implies an upsert, but this is not explicitly communicated, leaving some ambiguity for an agent.

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%, with both parameters described (note text and post ID). The tool description repeats the purpose but adds no new meaning beyond the schema. The baseline of 3 applies because the schema already documents the parameters adequately.

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?

The description clearly states the action (add or update) on a specific resource (personal note on a saved post). It is unambiguous and distinguishes from siblings like get_notes (which reads) and delete_posts (which deletes), even without naming them.

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?

The description implies usage (to attach a note to a saved post) but does not explicitly compare with alternatives or mention exclusions. It sets a precondition (saved post) but offers no guidance on when not to use it or when a sibling like get_notes would be more appropriate.

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