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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint), and the description adds the genuinely non-obvious behavioral fact: public streams need no sign-in while private streams require a linked account with access. The enumeration of returned fields (description, publication state, API-access flag, pricing, custom-target instructions) is largely duplicative of the output schema, so it stops short of a 5.

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?

Four tight sentences, front-loaded with the purpose, then scope bound, then return content, then auth prerequisite, then the exclusion. No filler and no repetition of the title.

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 single-parameter read tool with an output schema, rich annotations and a clear sibling neighborhood, the description covers purpose, prerequisites, return shape and exclusions. Nothing an agent needs to call it correctly is missing.

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?

With one required parameter at 100% schema coverage, the baseline is 3. The description adds useful semantics beyond the schema by telling the agent where the ID comes from (search or streams_all) rather than just that an 'id' string is required.

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+resource ('Inspect a discovered Synoptic feed by ID') and immediately bounds scope with 'Does not return posts or follow the stream', which cleanly separates it from get_stream_posts, search_stream_posts and follow_stream. An agent can distinguish it from all ~70 siblings without 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 explicit when-to-use framing ('before reading, configuring monitoring targets, or planning an API integration'), names the discovery alternatives ('Use search or streams_all to find an ID'), and states an explicit non-use case (no posts, no follow). Nothing material is left to inference.

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