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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, but the description adds cost/auth context ('Free, no payment or account required'), error semantics ('404 not_found if the id does not exist'), and hints at payload contents (next_actions, live trust-score badge). It does not mention rate limits or pagination, which is a minor gap given a single-record fetch.

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 the core action and scope, then the alternative, error case, and cost in descending priority. Three short sentences with no real waste, though the trust-score badge detail is slightly decorative relative to the rest.

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?

No output schema exists, so the description appropriately sketches the return shape (full record, next_actions, badge) and covers the failure mode and access cost. An agent has enough to call it correctly; only edge behaviors like very large records are unaddressed.

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?

Only one parameter and the schema already documents it fully at 100% coverage (UUID, sourced from search_listings). The description adds no format or syntax detail beyond what the schema states, so baseline 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 specific verb and resource ('Fetch one listing by id') and pins the exact underlying operation ('the full record GET /listings/{id} returns'). It explicitly contrasts itself with the sibling describe_listing, so an agent can route without opening either 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?

Names the alternative tool and the exact condition that selects it: 'For connection steps and payment steps in one place use describe_listing.' The schema also points to search_listings as the source of ids, closing the discovery loop.

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