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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable behavior beyond that: it is historical evidence lookup, does not make a live HTTP request, only works for an existing probe ID, and surfaces derived insights like counts and verdict changes. It stops short of describing the exact response format, but the provided behavioral context is strong.

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 sentences with no fluff: core capability first, then specific use cases, then an explicit alternative. Every sentence adds distinct value and the key differentiator (no new HTTP request) is 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?

For a two-parameter read-only tool, the description covers what it returns conceptually, when it should be used, what it should be used after, and when it should not be used. Even without an output schema, an agent has enough context to invoke it correctly and interpret the results.

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 0%, so the description carries the explanatory burden. It contextualizes probe_id as an existing Probe experiment ID obtained after verify_http_claim and links the 'up to 20' cap to the limit parameter's maximum/default. It does not restate the hex format or allowed limit range, but those are already in the schema, and the usage context adds real meaning.

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 ('Retrieve'), a precise resource ('persisted observations for an existing Probe experiment ID'), and an explicit scope cap ('up to 20'), and immediately distinguishes it from the sibling by noting it makes no new HTTP request. This lets an agent recognize the tool and separate it from verify_http_claim without reading 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?

It gives an explicit trigger ('Use after verify_http_claim'), lists the inspection use cases (repeated results, PASS/FAIL/ERROR counts, agreement, verdict changes), and states the exclusion condition: use verify_http_claim when freshness or present endpoint behavior matters. Both when-to-use and when-not-to-use are unambiguous.

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