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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by disclosing stability guarantees: the opaque id is unique within the app and unchanged across token refresh, reconnection, and display-metadata changes, which tells the agent the value is safe to cache and compare over time.

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?

Two tight sentences, front-loaded with the core action and followed by the one non-obvious behavioral guarantee. No filler, no repetition of the tool name or 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?

An output schema exists, so return-value structure need not be restated, and annotations cover the safety profile. For a zero-parameter read tool, the description supplies everything an agent needs: what identity is returned and the stability semantics of the id.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The schema itself has no properties to describe.

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 ('Return the profile') scoped to 'this request's authenticated credentials', which is precise and unambiguous. It does not name or contrast any sibling, but the autoposter_* siblings are all post/media operations, so the identity tool is naturally distinguishable without the description having to say so.

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?

There is no explicit when-to-use, when-not-to-use, or alternative-tool guidance. The phrase 'represented by this request's authenticated credentials' weakly implies 'use this to identify the calling account', but an agent gets no routing instruction and no stated prerequisites (e.g., what happens if credentials are invalid).

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