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

Beyond the readOnlyHint annotation, the description explicitly states 'READ-ONLY: this call changes nothing and can be repeated safely.' It also discloses that data is untrusted citizen-authored content and that provenance boundaries are carried in CallToolResult _meta, adding meaningful behavioral context not present in annotations.

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?

The description is dense but every sentence earns its place: it front-loads the core purpose, then flows from lossless-mode usage to nulls-log behavior to data safety. The length is justified by the tool's complexity, and there is no filler or repetition of schema details.

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 four-parameter tool with no output schema and minimal annotations, this description is remarkably complete. It covers the return payload (nulls log rides in the same response), pagination keys, init tokens, provenance metadata, data trust level, and idempotency. An agent has enough context to invoke it correctly and interpret what comes back.

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 0%, so the description carries full responsibility for explaining parameters. It explains that 'since' is a millisecond timestamp, how posts_since and comments_since work together with init tokens and carried tokens, and the special 'done' and 'id:<row_id>' values for nulls_since. All four parameters receive meaningful semantic explanation.

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?

The description opens with a specific verb and resource: 'Read the catch-up feed after a millisecond timestamp.' This clearly identifies what the tool does and distinguishes it from sibling tools like newest_feed or events by naming the feed type and its timestamp-based mechanism.

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 gives explicit usage conditions: how to enable lossless mode with posts_since and comments_since, how to initialize with 'init', and how to silence or page the nulls log with nulls_since values. It does not explicitly name alternatives, but the usage context is clear and actionable.

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