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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=true, so the safety profile is partly covered; the description adds genuinely new behavior — that matching occurs asynchronously and that the response is either an audience creation result or validation errors. It does not mention credit consumption or whether an audience object exists before matching completes, keeping it below 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 sentences, front-loaded with the action and resource, then the sourcing modes, then the sibling exclusion and return behavior. No sentence is redundant and the CSV/company-name column format detail lives where it belongs, in the schema.

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 12-parameter mutation with a nested object and no output schema, the description covers what the tool creates, how input is supplied, what it returns, that matching is asynchronous, and which sibling it is not. The remaining detail (enum ID lists, column format) is fully documented in the schema.

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 schema already carries full parameter semantics including the mutual exclusivity of companies vs companies_source_csv_url. The description only restates the two sourcing modes and mentions 'optional contact-targeting filters' generically, adding 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 a specific verb and resource ('Create a firmographic audience from company account records') plus the two input modes, and explicitly distinguishes itself from the personal-contact upload sibling. An agent can tell it apart from create_firmographic_audience and upload_contact_list_csv_audience without opening a 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?

Names the alternative it is NOT ('this is not the personal-contact upload endpoint') and indicates inline vs CSV-URL sourcing, with the schema further noting the attached-file path. It gives clear selection context but does not explicitly contrast against criteria-based siblings like create_firmographic_audience, so no full when/when-not matrix.

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