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

Annotations only cover the read-only safety profile; the description adds substantial context beyond that: default newest-first ordering, that records come back as data, and a detailed disclosure that a record's message_author varies by lead origin (manual note vs. chat summary vs. scan output vs. the lead's own words). It even sets a downstream behavioral constraint (never quote a message back unless the lead wrote it), which is exactly the kind of non-schema information an agent cannot get elsewhere.

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 first sentence is well front-loaded with scope and ordering, but roughly two-thirds of the text is a single field's semantics, delivered with caps emphasis and repeated prohibitions ("Never quote... never write 'you said'..."). The content is valuable but over-weighted for a list tool whose primary job is enumeration.

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?

With no output schema, the description does carry some of the return burden ("lead records as data", plus the message_author field contract), and it covers the safety profile via annotations. It omits pagination/cursor behavior and whether counts or truncation are signaled, which is a real but modest gap for a 4-optional-param list tool.

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 all four parameters (including the limit ceiling of 100) are already documented in the schema. The description restates the source/status/since filters without adding syntax or interaction detail, and never mentions limit at all. Baseline 3 applies.

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 ("List leads for this account") plus an ordering guarantee ("newest first"), which is enough to separate it from get_lead (single record) and list_lead_messages. It never names a sibling explicitly, so differentiation is inferred from the read/list semantics rather than stated.

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?

It gives concrete filtering axes (source, status, created-after) that imply when the tool is useful, but offers no when-not guidance and never points to list_lead_messages or get_lead as the alternative when the agent wants message bodies or a single lead. Usage is implied rather than directed.

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