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

Annotations only indicate readOnlyHint=false and destructiveHint=false, leaving the description to explain behavioral details. The description discloses that adding a post the user cannot read results in a 'not found' error, and that adding a duplicate post causes a 'CONFLICT'. These are important behavioral traits beyond the schema, though it doesn't mention permissions or side effects.

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 concise at three short paragraphs, front-loading the core action. Every sentence adds value—purpose, note rationale, and edge cases. No waste.

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?

Given the output schema exists, the description doesn't need to explain return values. It covers the core operation, note semantics, read-gate constraint, and duplicate conflict. However, it doesn't mention if the collection must exist or if the post must be visible to the user, which are minor completeness gaps for a moderately simple tool.

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%, so the baseline is 3. The description adds meaning beyond the schema by explaining the purpose of the note ('say what the reader gets from this one') and clarifying that collection_id must be yours. This extra context justifies a 4.

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 ('Append a post to one of your collections') and distinguishes it from siblings like colony_create_collection and colony_remove_from_collection. It also explains the unique value of the optional note, making the tool's purpose highly specific and differentiated.

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 implicitly explains when to use the note (to add value beyond a link list) and notes a constraint: a post past its read gate cannot be added. It does not explicitly mention alternatives or when not to use this tool compared to siblings like colony_bookmark_post or colony_create_collection, but the context is clear enough for a focused action.

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