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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-redundant behavior: a deterministic response, an explicit 404 unknown_listing error for a bad id, and that no payment or account is needed.

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 value proposition, followed by a dense but purposeful enumeration of returned content and two short sentences on error/determinism/cost. No filler, though the middle clause is a long parenthetical list that a reader must parse carefully.

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?

There is no output schema, so the description correctly carries the burden of describing return values, and it does so thoroughly (connection steps, payment summary, verification rule count, trust signals, warnings). Error behavior, determinism and cost are also covered, leaving only pagination/filtering depth unaddressed, which is not applicable here.

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%, so listing_id, agent_id and trace_id are all documented in the schema itself (including the 'UUID, e.g. from find_agents' hint). The description adds only the indirect point that a missing id yields 404; with the schema doing the heavy lifting, 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?

The description names a clear verb and resource (describe one listing) and enumerates exactly what it returns: how_to_connect steps, payment summary, verification template, trust signals, and warnings. It is specific enough to be actionable, but it never distinguishes itself from the similarly named sibling get_listing, leaving the agent to infer the difference.

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?

'Everything an agent needs to use one listing, in one call' implies the usage context (call this when you need to actually consume a listing), and 'Free, no payment or account required' removes a potential gating concern. However, no when-not condition or named alternative (e.g. get_listing vs describe_listing) is given, so routing 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.