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

Goes well past the readOnly/idempotent annotations: result ordering, the meta.notFound behavior for suspended/deactivated/unknown ids, the no-charge rule for those, and the exact price model (1 credit + 2 credits per profile). Those are the cost and failure-mode facts an agent cannot get from annotations or schema.

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?

Five short sentences, front-loaded with what it does and the primary use case, then ordering, then failure handling, then billing. Nothing is redundant with the schema or the annotations.

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?

There is no output schema, and the description compensates by disclosing the one return detail that matters (order preserved, misses in meta.notFound). For a single-parameter read tool with full annotations, no gaps remain that would cause a mis-call.

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 the `ids` description already covers comma-separated, 1-100, no spaces, duplicates ignored. The prose only restates the id cardinality and adds ordering semantics, so per the high-coverage baseline this sits at 3.

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 ('Get up to 100 public X profiles by id') with the cardinality limit baked into the first clause. That immediately separates it from the single-profile get_x_user and the name-based search_x_users without the agent opening a 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?

Gives an explicit use case — 'hydrating ids you already hold, such as post authors or followers' — which implies the boundary against search_x_users and get_x_user. It stops short of explicitly naming those alternatives or stating when not to use it, so it is clear context rather than a full routing rule.

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