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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description earns credit by disclosing what the digest actually returns (summary, highlights, risks, guidance, key metrics, and artifact links), which the annotations do not convey. It lacks any note on auth or rate limits, hence not a 5.

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?

Three tight sentences, front-loaded with the digest description followed by invocation and the read_document alternative. Zero filler; every clause carries actionable 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?

For a read-only tool with no output schema, the description adequately covers what is returned, how to invoke it, and the alternative for raw text. It could be marginally richer on the required-input combination (e.g. symbol vs doc_id tradeoffs), but nothing essential for correct invocation is missing.

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 every parameter including the symbol/ticker/identifier aliases and the doc_type enum is already documented in the schema. The description only reinforces the doc_id-vs-doc_type selection rule that the schema already states, so it adds little beyond the structured data; baseline 3 is 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 the specific resource ('investor digest of ONE parsed filing') and enumerates its contents (summary, highlights, risks, guidance, key metrics, PDF/Markdown links). It distinguishes itself from siblings by naming read_document for raw text and list_company_documents as the source of doc_id, so an agent can route correctly 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?

Explicitly tells the agent how to invoke it (doc_id from list_company_documents, or doc_type for newest of that type) and names the alternative when the raw text is wanted ('For the text itself use read_document or download links.markdown_url'). This is clear context plus an alternative with a selecting condition; it stops short of full when-not guidance across all siblings.

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