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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description goes further and adds real operational context: no API key required, the exact upstream sources consulted (OpenAI/Anthropic/Google deprecation pages), data provenance with read dates, and the crucial negative-result semantics that 'retiring: false' means absence from those pages rather than a guarantee.

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?

Core purpose is front-loaded in the first clause, and each subsequent sentence carries information. The long comma-list of returned fields is dense but justified since there is no output schema; still, it is close to exhaustive rather than optimally trimmed.

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 must describe return values, and it does so fully: status, shutdown date, replacement, price ratio, documented API changes, and source URL with read date. Combined with the negative-result explanation and source scope, an agent has everything needed to call and interpret it.

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 already documents prefix handling and fine-tuned ID matching, so the baseline is 3. The description still adds value by emphasizing 'as your code or config names them' and enumerating concrete ID styles across three providers, which reinforces the accepted format.

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?

Opens with a direct question that names both the verb and resource ('Is this model retiring?' / 'returns every announced shutdown'), and scopes it to language models only. It is clearly separable from siblings like agentcheck_api_sunsets and agentcheck_get_pricing without opening any schema.

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?

Tells the agent the trigger condition (checking whether a model ID is retiring) and constraints ('Language models only', 'No API key needed'), plus how to supply IDs from code/config. It does not explicitly name which sibling to use for non-model deprecations, so no exclusions are stated.

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