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

Even though annotations already declare readOnly/openWorld/idempotent non-destructive behavior, the description adds substantial behavioral detail: underlying data sources (SEC EDGAR, GDELT→GNews fallback, USPTO), rate-limit fallback logic, and the soft-failure due to PatentsView API sunset. It also discloses output structure and citation URIs.

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?

The description is dense and packed with useful information, though it is a long run-on sentence. Every clause adds value, and the structure is acceptable for a multi-source tool, but a more bulleted or segmented layout would improve scannability.

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?

Given there is no output schema, the description compensates by explicitly stating the return shape (changes[], total_changes, citation URIs) and covering all major behavioral aspects: sources, fallback, date formats, and alternative tool. It is complete for a tool of this complexity.

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 description coverage is 100%, so the baseline is 3. The description restates the `since` formats and value examples already present in the schema, adding little new parameter-specific meaning. It does reinforce typical usage ('30d' or '1m') but not enough to exceed the baseline.

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 clearly identifies the tool as a 'change feed for a company in the last N days/weeks/months', with specific verbs like 'Fans out' and explicit scope. It also distinguishes itself from the sibling tool entity_profile by contrasting dynamic changes with static profiles.

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?

Provides explicit usage context through query examples ('What's new with X', 'latest on Y') and gives a direct when-not-to-use directive: 'Use entity_profile instead when you want the static profile'. This makes the selection boundary clear.

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