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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-obvious context: partial-update semantics ('only the fields you pass change') and the concrete endpoint (PUT /companies/{id}). It stops short of explaining what is destroyed (e.g. tag_ids replacing the whole list) or auth/error behavior, so 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?

A single compact sentence with the mutation type front-loaded, the key semantic in the middle, and the endpoint last. No filler, no repetition of schema details.

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 15-parameter mutation with a nested custom_fields object, full schema coverage and rich annotations, the description supplies the one thing structured data cannot: the partial-update contract. Not all gaps are closed (clearing fields, list-replacement behavior for tag_ids), and with no output schema it says nothing about what is returned, so 4.

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% with all 15 parameters documented in-schema, so the baseline is 3. The description adds one meaningful rule beyond the schema, namely that omitted fields are left untouched, but gives no per-parameter guidance (e.g. how to clear a value, or that tag_ids is a full replacement list).

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 ('change fields of a company') and prefixes it with 'WRITE:', which distinguishes it at a glance from pipelinecrm_get_company and pipelinecrm_list_companies. It does not explicitly name a sibling or contrast with pipelinecrm_create_company, so 4 rather than 5.

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?

The clause 'only the fields you pass change' gives an implicit usage rule (pass only what you intend to modify) and the PUT endpoint signals the target path. However, there is no stated when-to-use versus pipelinecrm_create_company, no prerequisites, and no exclusions, so usage remains implied rather than explicit.

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