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

Annotations already declare readOnlyHint=true, destructiveHint=false and a closed world, so safety is covered. The description adds genuinely non-obvious behavior: metadata search is free while purchased execution and deliverables are not, and results are limited to active public listings. It stops short of noting pagination limits, which the schema already documents.

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 with the scope banner front-loaded and every prohibition paired with a redirect. No filler, and the routing information is placed where an agent will read it first.

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 an output schema present and annotations covering the safety profile, the description only needs to establish scope and routing, which it does completely. Nothing required to call this 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?

Schema description coverage is 100%, so all eight parameters (query, category, provider, deliveryType, price bounds, limit, offset) are already documented in the schema. The description enumerates the same filter dimensions without adding syntax, units, or format guidance beyond the schema, so baseline 3 is correct.

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 (search) and resource (active public marketplace capabilities) and immediately constrains the scope to filtered discovery. It explicitly distinguishes itself from catalog.list, offers.list, and capability.get by name, so an agent can route without opening schemas.

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 ('when one or more filters are known') and two explicit when-nots with named alternatives (catalog.list for unfiltered browsing, offers.list for CrossingKey offers), plus a routing note to capability.get for exact IDs. This is the full when/when-not/alternative pattern.

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