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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world, so the safety profile is fully covered structurally; the description's 'read-only' restates it. It adds the precondition about needing a complete contract, but says nothing about failure behavior when the capability id is unknown or the input doesn't match the contract's inputSchema. Some added context, but not rich.

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, no filler, with the core action and its precondition front-loaded before the fallback guidance. Every clause carries routing information.

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?

An output schema exists, so return values needn't be explained, and annotations cover the safety profile. The description supplies the key invocation precondition (contract must be available) and the read-only nature. It could still say more about behavior when the contract is incomplete or the capability id is invalid, but it is adequate for this complexity.

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 both parameters (capability id and passthrough input object) are already documented in the schema. The description reinforces that the capability comes from a 'complete contract' and the input must match the discovered inputSchema, but adds no syntax or format detail beyond the schema. Baseline 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 and resource ('Run one read-only capability') and its precondition ('using an available complete contract'), which separates it from the mutation sibling capability_mutate via the 'read-only' qualifier. It does not spell out the mutation/query split explicitly, so sibling differentiation is implied rather than stated.

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 second sentence gives an explicit when-not condition and routes the agent: use search or describe only when the contract is missing, otherwise run this. That is clear context for choosing between this and capability_search/capability_describe, though the alternatives are named generically ('search or describe') rather than by tool name.

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