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

Goes well beyond the readOnly/openWorld annotations: it discloses the ordering of replies, the fromAccount flag on the account's own replies, and two hard prerequisites — the owner-only 'Let AI assistants answer comments and messages' setting and a connection authorized with comments/chat permissions. It even names the failure mode (MCP_INBOX_DISABLED) and the remediation (reconnect, or remove and re-add the client registration), which an agent could not infer from annotations alone.

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?

Front-loads what the tool returns, then the usage rule, then prerequisites — a sensible order with no filler sentences. The final prerequisite sentence is dense and long, packing setting name, error code, and two reconnect paths together, which slightly hurts scannability.

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 read tool with an output schema already covering return shape, the description still supplies everything an agent needs to call it successfully: permission requirements, the specific error it will hit without them, and the reconnection remedy. Nothing material is left unstated.

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%, so commentId (from list_comments) and the multi-organization rule for organizationId are already documented in the schema. The description adds no format or selection detail beyond that, so the baseline of 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 and resource — read one comment with its whole thread — and enumerates exactly what comes back (root comment, replies oldest first, media with caption and permalink). This clearly separates it from list_comments (enumeration) and reply_to_comment (mutation).

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 workflow rule: read the thread before replying so you don't answer a question the account already answered. That is real when-to-use guidance, but it never names an alternative sibling (list_comments, reply_to_comment) or a when-not-to-use condition.

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