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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile needs no repetition. The description adds genuine context beyond that: the meaning of each returned field and how create_api_key enforces them when minting a key (default when ttlDays is omitted, enforced limits). This tells the agent what the values signify and how they behave downstream. It omits error behavior, but the read-only, zero-param nature makes that a minor gap.

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?

Two sentences, zero filler. The primary purpose is front-loaded ('Return the project's key policy'), followed by precise field semantics and a routing note. Each clause earns its place — the create_api_key references explain why the returned fields matter without bloating the description.

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 zero-parameter, read-only tool with no output schema, the description is complete: it enumerates the return fields, explains their semantics, and names the mutation sibling. The annotations carry the safety profile, so nothing an agent needs to invoke this tool correctly is missing.

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?

The tool has zero parameters and the schema confirms this with an empty properties object, so there is nothing to document. The description correctly focuses on the return values instead, which is the relevant semantic content. Per the baseline for zero-param tools, a 4 is appropriate.

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 opens with a specific verb and resource pair — 'Return the project's key policy' — then enumerates the exact fields returned (defaultKeyTtlDays, maxKeyTtlDays, editorsMayCreateNonExpiringKeys). It differentiates from its sibling set_key_policy by framing get as the read counterpart and clarifying that these values are what create_api_key consumes.

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 routes the agent: 'use set_key_policy to change these values' names the alternative tool and the condition that selects it (mutation vs. read). It also clarifies the relationship to create_api_key, telling the agent that this policy governs key minting defaults and limits, which helps decide when fetching it is relevant.

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