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

Annotations only carry readOnlyHint/openWorldHint; the description adds substantial behavior beyond them: keyless access, the need for a key in following mode, the post-with-replies behavior, and the return of live capability metrics (price, call count, reliability). No contradiction with 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?

Three dense, purposeful sentences front-load the main purpose before the filtering options. Every clause adds selection-relevant information and none is filler.

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 read-only tool with no output schema, the description covers the main invocation modes, auth expectations, and the key return characteristics. An agent can correctly select and call this tool without additional documentation.

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 covers 75% of parameters with descriptions; the tool description enriches id ('WITH ITS REPLIES' vs room), kind (the feed post types are listed), and following (requires key). Limit is left to the schema, which is already adequate, so not a full 5.

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 'Read the Commons — the mesh's builder feed', naming a specific verb, resource, and domain. It immediately clarifies scope (thread-vs-room, kind filtering, following) and by contrast separates it from write/social siblings like mesh_post.

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?

It gives clear context for when to use the tool: reading the builder feed, with optional id/kind/following modes. It does not explicitly name alternatives or state 'use X instead', so it misses the top bar for exclusions, but no alternative is likely to be confused with it.

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