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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds a concrete failure mode (404 when the slug is not found), which is genuinely useful behavioral context, but it does not say whether an existing location assignment is replaced or what happens to the previous association.

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 short sentences, front-loaded with the operation and followed by the error behavior. The only waste is the repeated title line, which duplicates the title field without adding 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?

With only two fully documented parameters, a complete annotation set, and an output schema covering return values, the description supplies what the structured fields do not: the assignment semantics and the 404 condition. The remaining gap — whether the prior location is unassigned — is modest given the surrounding metadata.

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 description's only parameter-relevant content — the 404 for a missing slug — is already stated verbatim in the location_slug schema description. It therefore adds essentially no meaning beyond the schema, which is the baseline 3 case.

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 states a specific verb and resource ('Assign an existing project location to a review by slug'), which is more precise than the title alone and distinguishes the operation from the sibling updateLocation, which edits a location entity rather than a review's location. It stops short of explicitly naming that sibling as the alternative, so it is clear but not fully differentiated.

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 only implied: the agent can infer this is the tool for re-pointing a review at a different existing location, and that the location must already exist ('existing project location'). There is no explicit when-to-use/when-not, no statement about prerequisites (e.g., that createLocation must be called first for new locations), and no guidance relative to siblings such as updateLocation or updateReviewVisibility.

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