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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond the schema: it discloses the authentication requirement ('Precisa do token edm_…') and sketches the payload's semantics.

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 compact sentences, front-loaded with what the tool returns, and the auth prerequisite is appended without padding. No filler or redundancy.

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 two-parameter read-only tool with full schema coverage and no output schema, this is nearly self-sufficient: it names the resource, the returned fields and the required token. Only the sibling routing (vigiar_compra vs this tool) is left to inference.

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 both 'id' and 'limite' are already documented in the schema, including the 1–100 range and default of 50. The description adds no further parameter meaning, making the baseline of 3 appropriate.

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 resource (eventos de uma compra vigiada) and the dimensions returned (o que mudou, de quê para quê, quando) plus the current snapshot. It is clearly distinguishable from the sibling vigiar_compra, which would create the watch, but it doesn't name that sibling 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 — call this to see the timeline of changes for an already-watched purchase — but there is no explicit when-to-use/when-not statement or reference to the alternative (vigiar_compra to start watching). Nothing misleading, just under-specified.

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