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

Annotations already cover the safety profile (readOnlyHint=false, openWorldHint=true, idempotentHint=false), so the description only needs to add context. It does add two non-obvious facts: Chirpie retains only the server from the supplied value, and an unresolvable server is rejected with the specific error code mastodon_instance_invalid. It does not say what the call returns or that the user must complete an external redirect, but the annotation bar is met.

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: the action is front-loaded, then the accepted inputs and the failure mode. No filler and nothing important buried.

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 one-parameter OAuth initiation tool with annotations carrying the safety profile, the description covers action, input leniency, retention behavior, and the failure case. The main omission is the return value or next step (e.g. an auth URL the user must visit), which matters since there is no output schema.

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 single parameter is fully documented there, so the baseline is 3. The description's "keeps only the server" adds the useful nuance that a handle or profile URL is accepted and normalized rather than stored verbatim, but otherwise restates what the schema already says.

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 ("Start the OAuth flow for a Mastodon account") and names the platform explicitly, which cleanly separates it from the sibling connect_* tools for Bluesky, X, Facebook, and the rest.

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 implies when to call it (a user wants to link a Mastodon account) and names the accepted input forms, but it never states when NOT to use it or routes the agent to an alternative, such as disconnecting or listing accounts. Usage is inferable rather than spelled out.

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