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

Annotations already declare readOnly/idempotent/openWorld, and the description goes well beyond them by disclosing the login requirement, the result truncation (only first 50 comments, ascending), and a precise failure semantic — all invisible cases (deleted, out-of-scope visibility, blocked) collapse to moment_not_found. This is exactly the extra behavioral context annotations cannot carry.

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 bracketed, front-loaded blocks — purpose, chain, pitfalls — with no filler. Every clause conveys actionable information (what is returned, what to chain, what the error means), so nothing can be trimmed without losing value.

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?

With no output schema, the description takes on the burden of describing returns (full text, likers, first 50 comments) and does so, plus covers the auth precondition, error code, and follow-up chains. Nothing an agent needs to call it correctly is missing.

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 already 100%, and the single momentId parameter's provenance (list_moments_feed / get_user_moments / search_moments ids) is documented in the schema itself. The description adds no further per-parameter detail, so the baseline 3 applies.

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 precise verb+resource: returns one moment's full text, its likers, and the first 50 comments in ascending order. It also distinguishes itself from sibling list/search tools (list_moments_feed, get_user_moments, search_moments) via the schema-implied single-id scope, so an agent can identify exactly what it fetches.

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 explicit sequencing: "reply to a comment, first call this to obtain commentId", then names the alternatives (comment_moment with replyToCommentId, like_moment) and even the downstream chain for attached cards (get_activity/get_product/get_need/get_organization). Routing and preconditions are spelled out rather than inferred.

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