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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=false, so the safety profile is fully covered by structured data. The description adds that the payload is informational content (dates, migration behavior, checklist), but says nothing about the form or depth of what is returned, which matters since there is no output schema.

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?

A single front-loaded sentence that names the dates first and then the migration/checklist content, with no filler. It is dense but every clause maps to a distinct payload section, so nothing should be cut.

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 reference tool with full annotation coverage, the description covers the substantive questions an agent would have, including the key caveat that custom Actions do not migrate. It stops just short of indicating the return format or how authoritative/long the guidance is.

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 takes zero parameters, so the baseline is 4. The description correctly implies a parameterless lookup and prevents an agent from expecting to scope the query by date or product version.

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 names a specific resource (custom GPT retirement in ChatGPT, December 2026) and enumerates the exact content: key dates, what migrates automatically, what does not (custom Actions), and a rebuild checklist. It is clearly distinct from the sibling tools (client setup, OpenAPI conversion preview) by content, though it never names those siblings explicitly.

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 implied by the content scope: an agent would call this when it needs retirement dates or a migration checklist. There is no explicit when-to-use framing, no statement of when this guide is NOT the right choice versus get_mcp_client_setup or preview_openapi_conversion, and no prerequisites noted.

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