diagnose_public_url

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

With no annotations, the description fully carries the burden. It discloses the probe location (gateway-us-east-1), cache warming effect ('the probe itself populates the cache'), the 'probeMayHaveWarmedCache' flag, return fields (expectedSha256, observedSha256, invalidation, hint), and error conditions (403 for out-of-project URLs, 400 for non-*.run402.com). No contradictions.

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?

Extremely dense yet clear: one sentence for purpose, one for use-case, two for return fields and behavior, and one for error conditions. No unnecessary words. Front-loaded with purpose, then essential details.

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 no output schema, the description fully explains return values (expectedSha256, observedSha256, invalidation, hint) and behavioral nuances (cache warming, error conditions). Covers all aspects needed for correct invocation and interpretation.

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 100% with basic descriptions. The description adds meaning beyond schema: it explains the URL format with an example ('https://app.run402.com/_blob/avatar.png'), notes restrictions on non-*.run402.com URLs, and implies the project_id ownership check. Provides useful context beyond the schema's simple labels.

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 clearly states it returns 'the live CDN state for a public blob URL' and gives specific use cases ('when a deployed asset shows the wrong version or you suspect cache staleness'). It distinguishes itself from other tools by noting it is 'probed once from gateway-us-east-1 — NOT a global view'.

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 describes when to use (cache staleness, wrong version). Provides constraints: not a global view, URL restrictions (403/400 errors). Does not directly name alternative tools but sets clear expectations. Lacks explicit 'when not to use' but sufficient for selection.

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