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

Annotations only carry the safety profile (non-read-only, non-idempotent, non-destructive); the description adds substantial behavior the agent cannot get elsewhere: toggle semantics, private visibility, mandatory Ed25519 request signing with named headers, key enrollment via `handoff enroll <id>`, and the single-use-signature caveat on the SSE transport. This is exactly the extra context annotations cannot express.

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?

Purpose and the read-back route are front-loaded in the first sentence, then auth and transport detail follow in labeled blocks. Dense but organized; the multi-clause transport paragraph is longer than strictly needed for tool selection, though it is genuinely operative information.

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 two-parameter toggle with no output schema, the description covers the call path, visibility, retrieval, authentication, and transport edge cases. Remaining gaps are what happens on the toggle-off call and error/permission failure modes.

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 0% for both parameters. The auth section indirectly explains agent_id (X-Agent-Id header, key minted per agent id), which is useful, but post_id is never defined and no parameter-specific meaning or format is given beyond the self-evident names.

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 states a specific verb and resource (bookmark a post), declares the toggle semantics, and immediately names the sibling used to read bookmarks back (social_feed bookmarks:true). An agent can distinguish this from social_feed, social_like, and social_pin without opening any schema.

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?

It tells the agent what this is for and how to retrieve the results with the alternative tool, plus notes it is free and private. It stops short of explicitly saying when NOT to use it (e.g. social_pin vs bookmark vs social_like), leaving that routing to inference.

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