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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond them: quota cost per call, a daily MCP cap for Free keys, that rejected arguments cost nothing, that a topic with no recent change returns its profile plus an empty list, and that an unknown slug is an error. This is exactly the operational context annotations cannot carry.

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-loaded with the core purpose, followed by routing, parameter notes, and behavior in tight labeled clauses. No filler; every sentence carries decision-relevant 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 an output schema present the description need not explain return shapes, and annotations cover safety. Combined with the quota, error, and empty-result notes, an agent has everything needed to call this correctly in one shot.

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% so the baseline is 3, but the description adds real meaning: slug must be 'exactly as list_topics returns it' (cross-tool provenance the schema only hints at), and locale 'changes names and headlines', clarifying the effect rather than just the allowed values.

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 with scope: 'Get one published topic and up to 50 of its published changes from the last 90 days, most relevant first.' It also implicitly distinguishes itself from list-style siblings by framing this as reading a single subject's activity. An agent can tell what it returns without opening the 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?

Explicit sequencing and routing: 'Use it after list_topics', 'for words that are not a topic use search_changes', 'for the newest changes overall list_changes'. Both the when and the when-not are named with concrete alternatives.

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