Get a performance metric by PPM ID

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

Annotations declare readOnlyHint=true and openWorldHint=true, covering the safety profile. The description then enumerates the returned payload (estimates with confidence intervals and standard errors, trait, phenotyping method, covariates, score, samples), which is genuinely valuable context given there is no output schema. It doesn't cover error/not-found behavior or the effect of the 'full' flag.

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?

A single front-loaded sentence that packs the identifier format and the returned content with no filler. Every clause (estimates, trait, covariates, score, samples) earns its place by describing the payload.

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?

A read tool with no output schema, so the description appropriately compensates by enumerating return contents. All three params are documented in the schema, and annotations cover safety. It would be stronger with explicit routing to search_performance_metrics, but it is otherwise complete for correct invocation.

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%, and the schema itself fully documents ppm_id, full, and fields. The description only reinforces the ppm_id format with an example and does not add meaning beyond the schema for full/fields, so the baseline of 3 applies.

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 ('Retrieve') and resource ('one reported performance metric') with a precise identifier ('by PPM ID'). The word 'one ... by PPM ID' implicitly contrasts with the single-retrieval nature versus search_performance_metrics, though it doesn't name the sibling explicitly.

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?

Usage is implied: 'one ... by PPM ID' suggests you must already know the ID, which differentiates it from a search tool. However, there is no explicit guidance on when to use this versus search_performance_metrics, and no exclusions or prerequisites are stated.

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