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

Annotations already declare readOnlyHint=true. The description adds context by describing a conditional behavior: in live mode a key is required, while test mode works without one. It also enumerates what the response includes (SLA, payment timing, etc.), going beyond the annotation.

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?

The description is a single, dense sentence that front-loads the tool's core and then appends the essential sandbox note. No filler or repetition.

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?

Given the tool's moderate complexity and no output schema, the description covers the important context: the response fields, the environment distinction, and the key requirement. It misses an explicit id format hint, but the rest is solid.

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 coverage is 0%, so the description carries the burden. It does explain the env parameter by associating it with sandbox reading, but the id parameter is only implied as the listing identifier. The description partially compensates but does not fully document both parameter semantics.

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 uses a specific verb+resource combination ('Full listing incl. input_schema, examples, SLA, payment timing, the seller and its response record') that distinguishes it from sibling tools like get_job or search_listings. The title 'Listing details' reinforces the purpose clearly.

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?

The description explicitly tells the agent when to use the test sandbox ('Without a key add env=test to read a sandbox listing'), which is a clear usage condition. It does not explicitly name alternative tools, but the guidance is actionable and contextually relevant.

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