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

Annotations declare readOnlyHint=false and destructiveHint=false, so this is a non-destructive write. The description adds meaningful behavior beyond that: the nonce is block-anchored and derived from (challengeId, latest blockHash, workOutputRoot) to prevent pre-computation, and TTL is clamped to 120 seconds. It omits auth needs or rate limits, but the added cryptographic and lifetime context is substantial.

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?

Three tightly packed sentences: purpose, required workflow step, then derivation and return shape. No wasted words and key constraints are front-loaded.

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 usefully lists the return fields (challengeId, nonce, blockNumber, maxAgeSeconds). It covers the challenge's role in the capture workflow and its anti-precomputation guarantee, so an agent has enough to call it correctly.

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 the schema already documents jobId, declaredClass, and requestedTtlSeconds. The description only repeats that maxAgeSeconds/requestedTtlSeconds is clamped to 120, adding no new syntax or constraint information beyond the schema.

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: 'Issue a fresh block-anchored CaptureNonceChallenge for a job.' This clearly distinguishes it from sibling capture tools like pcc_capture_upload and pcc_capture_anchor.

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?

Explicitly says the operator's device must render the nonce into captured media before calling pcc_capture_upload, which gives clear sequencing and names the next tool. It does not say when not to use this tool or list alternative challenge mechanisms, but the context is strong.

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