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

Annotations already declare readOnly/idempotent/openWorld=false, so safety is covered; the description goes further by disclosing cost and payment path ('Upstream quota, then $0.003 via x402'), the full return field set, and an alias name ('Also callable as get_model'). It stops short of describing error/rate-limit behavior or evidence freshness semantics in detail, so a 4 rather than 5.

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?

Front-loads the core operation, then usage, then exclusions, then return values and cost. Every sentence adds distinct information with no filler; dense but not padded.

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 no output schema, the description compensates by naming the return fields (verdict, recommended_action enum values, replacement, shutdown_date, evidence, freshness) and the cost/quota path. Combined with the trigger conditions, an agent has everything needed to call it correctly.

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 coverage is 100% and the schema descriptions already say model is preferred and id is a legacy alias, so the description's 'Prefer model; id is only the legacy argument name' largely restates structured data. Baseline 3 applies since the schema carries the parameter burden.

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 (read/determine) and resource (one LLM model id's deprecation state) and enumerates the outputs: active/deprecated/retired, shutdown date, replacement. It explicitly differentiates itself from check_api_status and list_recent_api_changes, so an agent can disambiguate without opening 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?

Gives concrete triggers ('before hard-coding a model id', 'when a call fails as model-not-found') and explicit exclusions with the correct sibling named for each ('Do not use it to see if the provider is down (check_api_status)', 'or to list many retirements (list_recent_api_changes)'). Both when-to-use and when-not-to-use are covered.

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