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

Annotations already declare readOnly/idempotent/non-destructive, and the description reinforces that ("changes nothing"). It adds genuinely new behavioral context: no token required, OAuth is self-service with no human review, pricing terms, and that calling federation_apply accepts the ToS. Minor redundancy ("changes nothing" restates readOnly) keeps it just below top marks.

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-loaded with purpose, then pricing, application steps, explicit Returns block, and example — all useful. The metaphorical phrasing ("the door's window / the door") and the dense pricing sentence add mild noise but do not obscure the core.

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?

With no output schema, the description supplies the return shape ({ offer, how_to_apply with step_1/step_2/note }), clarifies offer matches /.well-known/comos-vendor.json, and explains the downstream apply flow. An agent has everything needed to call it and interpret the result.

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 optional `channel` param is fully documented in the schema as telemetry-only. The description adds nothing about `channel` and only supplies a no-arg example, so it neither compensates nor harms beyond the schema baseline.

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 ("Read the ComOS network's vendor offer") plus access scope (public, read-only, no token) and explicitly contrasts with the sibling federation_apply ("the door's window ... federation_apply is the door"). An agent can distinguish it from the large federation_* family 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 an explicit call sequence: read this offer, obtain an OAuth token (self-service, no human review), then call federation_apply with it. It names the alternative (federation_apply) and the condition that selects it, and provides a literal example invocation.

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